oom: make sure that TIF_MEMDIE is set under task_lock

[linux-beck.git] / mm / oom_kill.c

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index f82dd13cca68bd85b3f407542cddc83fb3ac3992..294493a7ae4b0ee5b809489ed1a1164736267ff8 100644 (file)
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -438,11 +438,14 @@ void oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
         * If the task is already exiting, don't alarm the sysadmin or kill
         * its children or threads, just set TIF_MEMDIE so it can die quickly
         */
-       if (task_will_free_mem(p)) {
+       task_lock(p);
+       if (p->mm && task_will_free_mem(p)) {
                set_tsk_thread_flag(p, TIF_MEMDIE);
+               task_unlock(p);
                put_task_struct(p);
                return;
        }
+       task_unlock(p);
 
        if (__ratelimit(&oom_rs))
                dump_header(p, gfp_mask, order, memcg, nodemask);
@@ -492,6 +495,7 @@ void oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
 
        /* mm cannot safely be dereferenced after task_unlock(victim) */
        mm = victim->mm;
+       set_tsk_thread_flag(victim, TIF_MEMDIE);
        pr_err("Killed process %d (%s) total-vm:%lukB, anon-rss:%lukB, file-rss:%lukB\n",
                task_pid_nr(victim), victim->comm, K(victim->mm->total_vm),
                K(get_mm_counter(victim->mm, MM_ANONPAGES)),
@@ -522,7 +526,6 @@ void oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
                }
        rcu_read_unlock();
 
-       set_tsk_thread_flag(victim, TIF_MEMDIE);
        do_send_sig_info(SIGKILL, SEND_SIG_FORCED, victim, true);
        put_task_struct(victim);
 }